Electro-magnetically operated electric switches



March 15, 1966 J, FEAVER 3,241,004

ELEGTRO-MAGNETICALLY OPERATED ELECTRIC SWITCHES Filed July 26, 1962 LEADS 3 flgil Inventor JOHN L NEL FEA ER 721ml, zamhfli 2M; 1%

Home y United States Patent Ofifice 3,241,004 Patented Mar. 15, 1966 3,241,004 ELECTRO-MAGNETICALLY OPERATED ELECTRIC SWITCHES John Lionel Feavcr, Burghfield Common, near Reading,

England, assignor to Pye Limited, Cambridge, England, a British company Filed July 26, 1962, Ser. No. 212,557 Claims priority, application Great Britain, July 27, 1961, 27 ,252/ 61 6 Claims. (Cl. 317-157.6)

The present invention relates to electromagnetically operated electric switches incorporating one or more switching devices.

According to the present invention an electromagnetically operated electric switch comprises a coil located upon a part of a magnetic circuit, said magnetic circuit having an air gap, and at least one switching device arranged in shunt with the air gap and which can be influenced by the magnetic field produced by a DC current flowing in the coil. The switching device or devices may consist of one or more reed contact sets, that is to say contact sets in the form of metal reeds, each set being sealed in an enclosing envelope which may be evacuated or contain a non-corrosive gas. Alternatively the switching device or devices may consist of one or more semiconductor devices whose conductivity changes in the presence of a magnetic field.

The magnetic circuit preferably comprises a laminated iron core in which case the total number of laminations may be divided into two or more groups arranged sideby-side in parallel planes with the switching device or de vices located between the groups or between successive groups of laminations and so that they bridge the air gap provided in the laminations. The coil may be located about the air gap so that it also surrounds the switching device or devices or may be located on another part of the magnetic circuit.

Advantageously, the coil can constitute a winding of a transformer wound on the core. The windings of such a transformer may carry AC. or pulse signals which are transformed according to the ratio between the transformer windings. Several switching devices may be incorporated in the transformer assembly.

Where switching devices comprising reed contact sets are employed one or more of the reed contact sets may have a winding or windings around its envelope through which can be fed a DC. current to produce a magnetic field serving as a bias to influence the point at which the contacts operate. This magnetic bias may assist the main magnetic field or may be in opposition so that a reed contact set is closed by the bias field and releases when the main field is present. Alternatively or additionally the point of operation of the reed contact sets may be influenced by energising one or more auxiliary windings on the transformer, in addition to those which carry A.C. signals and possibly a D.C. current for the operation of the reed contact sets.

In order that the invention may be more fully understood reference will now be made to the accompanying drawings in which:

FIG. 1 is a somewhat diagrammatic side elevation of one construction of electric switch according to this invention incorporating a transformer. FIG. 2 is an inverted plan of the parts shown in FIG. 1 with part of the core removed and FIG. 3 is a circuit diagram showing one possible arrangement of transformer windings and auxiliary windings for operating the reed contact sets.

Referring to FIGS. 1 and 2, the transformer comprises a magnetic core consisting of a plurality of laminations 1 having three parallel limbs and whose central limb extends through a bobbin 2 on which is wound the transformer windings 3. The central limb of the core also includes an air gap to prevent saturation of the magnetic circuit by the DC. current fed to the windings. The laminations are divided into two groups 4a, 4b arranged side-by-side in parallel planes and a plurality of reed contact sets 5 are arranged between the two groups within the bore of the bobbin so that they bridge the air gap in the magnetic circuit.

FIG. 3 shows the electrical circuit of the transformer assembly shown in FIG. 1. The windings 3P, 38, which extend in practice around both the central limb of the laminations and also the reed contact sets, are arranged to carry A.C. signals which generally have substantially no effect on the reed contact sets 5 and which are transformed according to the ratio between the windings, whereby the device functions as a transformer for A.C. signals. However, by providing any of the windings with the appropri: ate DzC. ampere-turns, the application of a DC. current to this winding or these windings will cause switching of the reed contact sets 5. The D.C. ampere-turns in two or more of the windings may be arranged to assist or oppose one another and the DC. current fed thereto may be continuous or pulsed, and can thereby provide for normal control functions such as gating. The further windings 6 are wound around the envelopes of the reed contact sets within the bore of the transformer bobbin and thus provide individual control of one of the reed contact sets independently of the others by the application of a suitable DC. current to the winding to produce a controlling magnetic field. Auxiliary winds such as 7 may also be provided on the transformer to carry a current which influences all of the reed contact sets.

Moreover, high level A.C. signals can be applied to any of the windings to provide intermittent control of the reed contact sets.

One application of a switch device according to the present invention is as a combined line transformer and switching device for use in telephone circuits. The DC. line current can cause actuation of a reed contact set when a telephone hand set is raised and the dialling pulses may also be conveyed by the operation of reed contact sets. The speech currents pass through the transformer windings to the various circuits as required. The devices can also be used for control systems as a logic element of high reliability and which have a high on/off impedance ratio. Moreover, the devices may be constructed as a ring counter or sequencing control device.

Whilst particular embodiments have been described it will be understood that various modifications may be made without departing from the scope of this invention. Thus the device may also incorporate one or more permanent magnets for assisting in the control or influence of the reed contact sets.

I claim:

1. A combined alternating current transformer and direct current operated switching device comprising in combination a laminated magnetic transformer yoke formed by two separate stacks of laminations mounted in fixed relationship side by side, each including an air gap in its magnetic circuit, a transformer primary winding upon said yoke and embracing said air gaps, a transformer secondary winding upon said yoke and embracing said air gaps, switch terminals adopted for connection to an external circuit, and a sealed reed contact set positioned between said two separate stacks of laminations in shunt with said air gaps and connected between said switch terminals whereby electrical connection between said switch terminals may be effected by the application of a direct current to either of said windings on said yoke without effecting the alternating current transformer operation.

2. A combined alternating current transformer and diaaaroo r rect current operated switching device comprising in combination a laminated magnetic transformer yoke formed by two separate stacks of laminations mounted in fixed relationship side by side, each including an air gap in its magnetic circuit, a transformer primary winding upon said yoke and embracing said air gaps, a transformer sec ondary winding upon said yoke and embracing said air gaps, switch terminals adapted for connection to external circuits, and a plurality of sealed reed contact sets positioned between said two separate stacks of laminations in shunt with said air gaps and connected between separate pairs of said switch terminals, whereby electrical connection between each pair of said switch terminals may be effected by the application of a direct current to either of said windings on said yoke without etfecting the alternating current transformer operation.

3. A combined alternating current transformer and direct current operated switching device, as claimed in claim 1, further comprising an auxiliary winding on said transformer yoke to carry a current which influences said reed contact set.

4. A combined alternating current transformer and direct current operated switching device, as claimed in claim 2, further comprising auxiliary windings on said transformer yoke to carry a current which influences said reed contact sets.

5. A combined alternating current transformer and direct current operated switching device, as claimed in claim 2, wherein at least one of said reed contact sets is provided with an individual control winding wound around the envelope of that reed contact set within the bore of the transformer so as to provide individual control of that reed contact set independently of the other sets, by the application of a suitable direct current to said control winding.

6. In a telephone circuit, a combined alternating current line transformer and direct current operated switching device comprising in combination a laminated magnetic transformer yoke formed by two separate stacks of laminations mounted in fixed relationship side by side, each including an air gap in its magnetic circuit, a transformer primary winding upon said yoke and embracing said air gaps, a transformer secondary winding upon said yoke and embracing said air gaps, switch terminals adapted for connection at an external circuit, and a sealed reed contact set positioned between said two separate stacks of laminations in shunt with said air gaps and connected between said switch terminals whereby electrical connection between said switch terminals may be effected by the application of a direct current to either of said windings on said yoke without effecting the alternating current operation of said alternating current line transformer.

References Cited by the Examiner UNITED STATES PATENTS 1,866,147 7/1932 Aylsworth a 317- 2,187,115 1/1940 Ellwood et al ZOO-87 2,261,323 11/1941 Zierdt 336178 2,342,781 2/1944 Aamodt 317-157.6 2,618,717 11/1952 Westin 317157.6 2,653,280 9/1953 Kiltie 317-1576 2,938,982 5/1960 Brown et al. 200-87 3,035,136 5/1962 Dal Bianco et a1. ZOO-97 SAMUEL BERNSTEIN, Primary Examiner.

BERNARD A. GILHEANY, Examiner. 

1. A COMBINED ALTERNATING CURRENT TRANSFORMER AND DIRECT CURRENT OPERATED SWITCHING DEVICE COMPRISING IN COMBINATION A LAMINATED MAGNETIC TRANSFORMER YOKE FORMED BY TWO SEPARATE STACKS OF LAMINATIONS MOUNTED IN FIXED RELATIONSHIP SIDE BY SIDE, EACH INCLUDING AN AIR GAP IN ITS MAGNETIC CIRCUIT, A TRANSFORMER PRIMARY WINDING UPON SAID YOKE AND EMBRACING SAID AIR GAPS, A TRANSFORMER SECONDARY WINDING UPON SAID YOKE AND EMBRACING SAID AIR GAPS, SWITCH TERMINALS ADOPTED FOR CONNECTION TO AN EXTERNAL CIRCUIT, AND A SEALED REED CONTACT SET POSITIONED BETWEEN SAID TWO SEPARATE STACKS OF LAMINATIONS IN SHUNT WITH SAID AIR GAPS AND CONNECTED BETWEEN SAID SWITCH TERMINALS WHEREBY ELECTRICAL CONNECTION BETWEEN SAID SWITCH TERMINALS MAY BE EFFECTED BY THE APPLICATION OF A DIRECT CURRENT TO EITHER OF SAID WINDINGS ON SAID YOKE WITHOUT EFFECTING THE ALTERNAING CURRENT TRANSFORMER OPERATION. 